The present technology relates to a communication apparatus and a communication system performing communication by proximity wireless transfer using a weak UWB signal, and more particularly, to a communication apparatus and a communication system performing communication by proximity wireless transfer in combination with non-contact power supply by electromagnetic induction, magnetic field resonance, or the like.
An example of a non-contact communication technology applicable to high-rate communication includes proximity wireless transfer technology “TransferJet” (trademark) (for example, see www.transferjet.org/ja/index.html (as of Jun. 23, 2011)). The proximity wireless transfer technology basically uses a scheme of transferring a signal by a coupling action of an induction electric field. A communication apparatus using the proximity wireless transfer technology includes a communication circuit unit that processes a high-frequency signal, a coupling electrode that is provided to be separated from a ground by a given height, and a resonance unit that efficiently supplies the high-frequency signal to the coupling electrode. In the specification, the coupling electrode or a unit including the coupling electrode and the resonance unit is referred to as a “high-frequency coupler” or a “coupler.”
As one of the characteristics of the proximity wireless transfer technology, high-rate data transfer of about 100 Mbps is realized using a weak ultra wide band (UWB) signal. Further, as another characteristic of the proximity wireless transfer technology, a transmission power is low. Therefore, since an electric field intensity (radio wave strength) is equal to or less than a predetermined level at a position 3 meters away from wireless equipment, that is, the electric field intensity is weak in a radio signal to the degree of a noise level in another wireless system located in the neighborhood of the wireless equipment, a user can use the weak radio signal without acquisition of a license (for example, see Japanese Radio Law Enforcement regulations (Radio Administrative Committee Rule No. 14 in 1950) Article 6.1.1).
For example, a communication apparatus in which a coupling electrode and a ground including a stub serving as a resonance unit are formed of a metal plate and which performs proximity wireless transfer has been suggested (for example, see Japanese Unexamined Patent Application Publication No. 2008-154267, FIG. 4). Further, an electric field coupler in which a coupling electrode is formed of a strip-shaped conductor and the volume of the metal is reduced, and a communication apparatus have been suggested (for example, Japanese Patent No. 4650536, FIG. 5).
A composite communication apparatus, in which the proximity wireless transfer technology is combined with electromagnetic induction type non-contact communication such as near field communication (NFC) which is a representative example, has been suggested (for example, Japanese Unexamined Patent Application Publication No. 2010-213197). In the composite communication apparatus, a coupling electrode of a high-frequency coupler is formed in the vicinity of an antenna coil for the electromagnetic induction type non-contact communication. An authentication or billing process associated with data transfer is performed through the electromagnetic induction type non-contact communication and large-capacity data is transferred through proximity wireless transfer, so that the communication processes can be completed by a single operation of a user and in a sense of the same access time as the time of the authentication and billing process of the related art.
Further, non-contact power supply of supplying power, rather than data, in a non-contact way has been known. In general, a coil is provided in each of a power reception apparatus and a power supply apparatus and non-contact power supply is performed by electromagnetic induction, magnetic field resonance, or the like. In such a non-contact power supply, a magnetic flux passing through a coil is interlinked with the metal such as a board inside an apparatus, and a problem may arise in that heat is generated in the communication apparatus by an eddy current occurring due to the electromagnetic induction. Therefore, a method of blocking the magnetic flux by a magnetic sheet to prevent the eddy current caused by the electromagnetic induction from occurring has been used (for example, see International Publication WO2007/080820).
FIG. 9A is a diagram illustrating the configuration of a coil (for power supply or power reception) disposed on a magnetic sheet, when viewed from an upper surface. FIG. 9B is a diagram illustrating the cross-sectional configuration of a non-contact power supply unit shown in FIG. 9A. A metal such as a board inside the apparatus is located below the magnetic sheet, although not illustrated in the drawing. Since the magnetic flux generated by the coil is blocked by the magnetic sheet, the magnetic flux does not reach the metal such as a board inside the apparatus. Accordingly, no heat is generated due to the eddy current inside the apparatus.
Hereinafter, a composite communication apparatus in which the proximity wireless transfer is combined not with the electromagnetic induction type non-contact communication but with the non-contact power supply realized by the electromagnetic induction will be examined. Since the composite communication apparatus can perform power supply and high-rate data transfer without using a cable, the convenience for a user is improved.
The coupling electrode of the high-frequency coupler is formed of a metal. Therefore, when the high-frequency coupler is disposed in the vicinity of the coil for power supply or power reception, the magnetic flux passing through the coil is interlinked with the metal portion such as a ground, and thus heat is generated due to the eddy current occurring due to the electromagnetic induction. Further, when the high-frequency coupler is disposed below the magnetic sheet to block the magnetic flux, a high-frequency wave signal of the proximity wireless transfer is blocked together, thereby deteriorating communication performance. For this reason, the disposition of the coupling electrode and the non-contact power supply coil is a technical task.
When the coupling electrode is disposed to be close to the non-contact power supply coil, there is an advantage in that touch points of the data transfer and the non-contact power supply become singular. FIG. 10A is a diagram illustrating the high-frequency coupler disposed in the vicinity of the central portion of the coil (for power supply or power reception) when viewed from the upper surface. FIG. 10B is a diagram illustrating the cross-sectional configuration of the high-frequency coupler and the coil. In the illustrated example, the high-frequency coupler is disposed on the magnetic sheet together with the coil. The metal such as the board inside the apparatus is located below the magnetic sheet, although not illustrated in the drawing. Since the magnetic flux generated by the coil is blocked by the magnetic sheet, the magnetic flux does not reach the inside of the apparatus below the magnetic sheet. However, it is apparent that the eddy current is generated due to the electromagnetic induction and thus heat is generated since the magnetic flux passing through the coil is interlinked with the metal portion such as a ground in the high-frequency coupler.
On the other hand, the high-frequency coupler can be considered to be disposed to be separated from the coil for the power supply or the power reception to avoid the influence of the magnetic flux from the coil for the power supply or the power reception. FIG. 11A is a diagram illustrating a coil (for power supply or power reception) and a high-frequency coupler formed to be separated from each other in a communication apparatus. In this case, to simultaneously perform power supply and high-rate data transfer by a single operation of a user, a transmitter and a receiver have to be designed and manufactured so that the gap between a non-contact power supply unit and a high-frequency coupler is aligned. Therefore, the non-contact power supply unit and the high-frequency coupler may not simultaneously face one another. Further, in regard to the touch points of the transmitter and the receiver, the non-contact power supply unit and the high-frequency coupler have to be disposed to face one another, and thus an operation of the user is troublesome. FIG. 11B is a diagram illustrating the non-contact power supply unit and the high-frequency coupler simultaneously facing one another between the transmitter and the receiver to simultaneously perform the power supply and the data transfer.
FIG. 12 is a diagram illustrating an example in which the non-contact power supply unit and the high-frequency coupler do not simultaneously face one another between the transmitter and the receiver since the gap between the non-contact power supply unit and the high-frequency coupler is not aligned between the transmitter and the receiver. When the gap between the non-contact power supply unit and the high-frequency coupler is not aligned, the touch points do not coincide with each other at the time of power supply and the time of data transfer. That is, when the transmitter and the receiver neighbor each other, the non-contact power supply unit and the high-frequency coupler may not simultaneously face one another, and thus the power supply and the high-rate data transfer may not be simultaneously performed through a single operation of the user. For example, it is necessary for the user to perform an operation of determining a position for communication to perform the data transfer and then changing the position to an optimum position for power supply to perform the power supply.